The objective of this project is to delineate the mechanisms of opiate involvement in parasitized animals and to understand the relationship between this opiate activation and behavioral abnormalities. White mice infected with the intestinal tract helminths Trichuris muris, Toxocaris canis and Schistosomatium douthitti will be examine din regard to opioid induced analgesia, changes in activity levels, social contact, and spatial learning in a water maze. The effects of a variety of opioid antagonist on these behavioral responses will be explored. The presence and secretion of POMC neuropeptides including beta-endorphin and Met-enkephlin as well as morphine will be examine din these parasites by HPLC and radioimmune assays. The effects of morphine and anandamide on the ganglia of Toxocaris canis will also be examined. Based on these studies, it is our expectation, that the basis of opioid behavioral alterations will be determined and establish a role for these signaling molecules in behavior that transcends analgesia, thus, having important consequences for psychiatry.